Sanding machine



May 4 l937. F. o. ALBERTsoN 2,079,143

SANDING MACHINE Filed Jan. 19. 1955 2Q 2 J6 if? J5 27 ieg/J7 Je? lPatented May 4, 1937 SANDING MACHINE Frans 0. Albertson, Sioux City, Iowa, assigner to Albertson & Company, Inc., Sioux City,Iowa,

acorporation oflowa' Application January 19, 1935, Serial No. 2,458y

4Ciaims.

The present invention relates to sanding machines, and particularly to improved methods and apparatus for the ventilation of sanding machine motors. s In the sanding machines of the prior` art,' the moving parts of the motor, especially the com-1 mutator.- have been subjected to severe wear and destruction on' account of the presence of v the abrasive particles resulting from the sanding operation. These abrasive particles include not only thesubstance which is ground off the automobile body, but the particles of emery and carborundum which forma part of the abrasive on the sanding wheel and which are worn off.A These abrasive particles are sucked in at the intake end ofthe ventilation system of the motor and come into direct contact with the commutator, causing such severe wear that the commutator often has but a small portion of the useful life which it should have in a commercially successful machine.

The motor 'structure is, of course, capable of general application and may be used upon electrical drills or driving motors `of any kind where f it is desirable to protect a. commutator and/or to provide special means for its cooling.

One of the objects of the invention is the provision of an improved ventilation system or method of ventilation and an improved apparatus by means of which the abrasive particles in the adjacent atmosphere are prevented from coming into contact with the commutator of the sandving machine motor.

Another objectv of the invention is the provision of an improved method and apparatus of the class described in which provision is also made for the removal of the heat from the vicinity of the commutator.

Another object of the invention. is the provision of an improved motor structure for sanding machine motors in which the motor is provided with an improved baffle arrangement capable of preventing abrasive particles from reaching the commutator and also capable of effecting the removal of the heat from the vicinity of the commutator.

Another object is the provision of an improved and simplied structure which may be readily applied or adapted to the existing motor structures and which may be manufactured at a very low cost.

Another object is the provision of an improved ventilation arrangement which requires no attention, replacement or cleaning, such as would be required if air, straining or cleaning elements lized in the present invention; and

were usedat the air intake to the' ventilation system of the motor.- l.

Other objects' and advantages'of the invention will `be lapparent from the following description and the accompanying drawing, in iwhich' sim- 5 ilar charactersof reference indicate similar parts throughout the several views.

Referring vto the single sheet of drawing, f

Fig. 1 is a view in perspective/of a sanding machine of the type constructed accordingv `to .10 the present invention; f l s Fig. 2 is a longitudinal sectionalview taken on vthe plane of the axis of the motor shaft, with the armature in elevationand the other vfragments of the motor in section, show'ingthe de- 15 .tails of construction of the present invention in section; l

Fig. 3 is a `transverse sectional View of the motor of Fig. 2, with the armature removed and with the housing in section on the plane of the line 3 3 of Fig. 2, showing the baille which directs the air coming in the intake in such manner as to prevent the grit from reaching the commutator;

Fig. 4 is a view in perspective'oi.' the baille uti- Flg. 5 is a sectional view of the baffle alone as it would appear if taken on the line 5-5 of Fig. 3.

Referring to Fig. i, the sanding machine in question preferably includes an electric motor I0 30 provided with a gear housing II having the laterally projecting drive shaft I2 which carries the sanding wheel I3. The gear housing is provided with a handle Il, and the motor is also provided with an axially extending handle I5 having a ball formation I6 for engagement in the palm of the hand. The rectangular or box-like formation I'I on the motor is a switch housing including the motor control switch I8 for starting and stopping the electric motor. 40

The sanding wheel I3 includes a suitable metallic base I9 and a resilient iiexible metallic disc 20 which supports a rubber disc 2|. 'I'lle rubber disc is covered on its forward face with a sheet of emery paper or. other suitable iiexible abrasive 22. The motor I 0 is provided with suitable ventilation openings 23 comprising the outlet openings and the inlet ventilation openings 24 at the opposite end.

The purpose of the present invention is the y protection of the moving parts of the motor from the grit or abrasive coming from the rotating sanding'disc 22 and drawn in through theopenings 24 at the top and bottom of the motor housing adjacent the switch housing 25. 55

Referring now to Fig. 2, the motor housing preferably comprises a substantially cylindrical member 26 which is provided with an inwardly curved end portion 21 terminating in a substantially rectangular end 28 to be joined to the switch housing 25.

The curved end portion 21 of the motor housing is provided with the longitudinally extending slots 24 previously identified as intake ventilation. openings. At the opposite end of the motor it is provided with an annular metal member 29 having slots 30 cut away and leaving the projecting cylindrical portions 3| for engagement with the wall of the motor housing 26 and for passage of the securing screw bolts 32. The slots 20 cooperate with the motor housing 26 in forming the outlet ventilation apertures previously identified with the numeral 23 and surrounding the periphery at the motor at the left end of Fig. 2.

The motor may be provided with any suitable type of bearings and with a shaft 33 supporting armature 34. Shaft 33 supports a fan 35 having blades 36 extending radially and longitudinal- 1y from the body of the fan 25. The commutator 31 is located at the opposite end of the motor shaft 33 and ordinarily is directly in line' with the path of the incoming air taken in at the apertures or slots 24.

The motors constructed according to the present invention are preferably provided with an inwardly extending cylindrical boss 33 surrounding the anti-friction bearing 39 which supports the right end of the shaft 33 in Fig. 2.

The cylindrical boss 33 may be utilized for supporting a baille 40 (Fig. 4) by providing the baffle 40 with an inwardly extending cylindrical formation 4| having a close frictional lit with the exterior of the boss 38. I'he baille is also provided with a pressed formation 42 for accommodating a boss formed on the interior of the motor housing for the purpose of housing a lubrication conduit, .but in other embodiments ofthe invention the formation 42 may be wholly omitted.

Battle 40 extends about the tubular or cylindrical formation 4l and curves outward and backward in the same direction as the tubular formation 4l, being provided with two main body portions 43, 44. It is also provided with laterally projecting attaching flanges 50 having apertures i for reception of the screw bolts 52 which are threaded into the body of the motor and which secure the baille against rotation on the boss 38.

Body portions 43, 44 are suitably curved so that they areP spaced from the interior of the motor housing 26, thereby leaving the ventilation space 21. The portions 43, 44 of the baille preferably extend into the motor housings far enough so as to overlap the motor field 45 and control the ow of all of the Ventilating air passing in at this end of the motor housing.

At a point which is preferably just beyond the end of the slots 24, each of the portions 43, 44 is provided with a slot 46, 41 formed by slitting the metal and pressing the material at one side of the slot upward and the other side downward. This forms a slot which extends in the direction of the plates 43, 44, and the slots are preferably so arranged that they open in toward the commutator.

The size of the slots 46, 41 is preferably smaller Vthan the'cross section of the adjacent ventilation conduit so that the slots 46, 41 represent only a small portion `of the cross section of the ventilation conduit at the intake end.

It will be observed that the slots 45, 41 are located just beyond the intake slots 24 and at a restriction in the intake line of the ventilation system. The arrangement is such, therefore, that the slots 46, 41 act like openings located at the restriction of a Venturi tube, and it is found that air is drawn in the direction of the arrows in Fig. 2 from the commutator 31.

The baiile 40 being arranged about the commutator in front of the ventilation slots 24, as shown in Fig. 3, it prevents the gritty air from coming into direct contact with the commutator and causes the air to pass on through the ventilation openings 43 which surround the field core 45. The heat generated through the friction and sparking at the commutator is dissipated by drawing the air out of the space surrounding the commutator through the Venturi tube slots 46. 41, and air is drawn into the space surrounding the commutator by natural ventilation; that is, through any other holes, apertures or cracks which lead to this space 43.

Many other methods of ventilation were tried before this method and apparatus were discovered, but none were so effective as the present structure including the baille and Venturi slots. By means of this arrangement the commutator is kept reasonably cool and the other parts of the motor are suitably cooled, but the gritty ventilating air is prevented from coming in direct contact with the amature, and its destructive action on the armature is eliminated or atleast so greatly reduced as to eliminate armatm'e trouble.

While I have illustrated a preferred embodiment of my invention, many modincations may be made without departing from the spirit of the invention, and I do not wish to be limited to the precise details of construction set forth, but desire to avail myself of all changes within the scope of the appended claims.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United-States, is:

1. In an electric motor, a motor housing provided with air intake and air outlet ventilation apertures, a motor in said housing provided with a fan, said motor having a commutator arranged adjacent the air intake openings and a baille arranged about said commutator to form a ventilation conduit between saidbafile and housing to deiiect from said commutator the air coming in said intake apertures, said conduit having a restriction to increase air velocity at that point and said baille being provided with a Ventilating aperture arranged near the restriction in the ventilation conduit between said baille and the motor housing whereby air is drawn from the space surrounding said commutator to discharge the heat from said commutator.

2. In an electric motor, a motor housing provided with air intake and air outlet ventilation apertures, a motor in said housing provided with a fan, said motor having a commutator arranged adjacent the air intake openings and a ban'le arranged about said commutator to form a ventilation conduit between said baille and housing to Vdeflect from said commutator the aircoming in said intake apertures, said conduit having a restriction to increase air velocity at that point and said baille being provided with a Ventilating aperture arranged near the restriction in the ventilation conduit between said baille and the motor housing whereby air is drawn from the space surrounding said commutator to discharge the heat from said commutator, said motor housing having a boss surrounding its drive shaft.

and said baille having a tubular formation iitting 5 on said boss to secure the bame in place.

3. -In an electric motor, the combination of a housing provided with ventilation apertures at each end, a motor field core spaced from said housing to provide a ventilation vconduit between 10 said core and housing, a motor armature carried by a motor shaft having a fan and commutator, and a baille carried by said motor housing in between said armature and certain of said ventilation openings to 4direct the air from said open-I tures at each end. an electric motos' in said housing comprising a field core spaced from said housing at certain points to permit ventilation around said core. and comprising an armature and commutator, a fan driven by said armature ing a ventilation conduit with said housing andV approaching said housing to form arestriction and said baille having an aperture located adiacent said restriction to eiect Venturi action whereby air is drawn through said aperture in saidbailleasaresultoithestreamofairiiowing over said baille from the intake ventilation apertures .of said housing to the outlet ventilation apertures, in order to. eilect a cooling of the armature and avoid the abrasive action of abrasive particles in the air on said armature.

mms oisrm'ison. 

